The present invention relates to coordinating typesetting and layout in desktop publishing (DTP).
DTP documents typically include multiple lines of glyphs, which usually represent characters but can also represent symbols and blank spaces. In a document, the lines of glyphs are arranged vertically, horizontally, or in some combination thereof. This arrangement can be applied to the entire document or any portion of the document. To aid in layout and typesetting, glyphs are usually arranged in a series of virtual bodies, sometimes referred to as emboxes. An embox defines an outer frame around a glyph and has dimensions and size. Generally, the size of an embox is determined by the type size of the character represented by the glyph framed. For example, an embox framing a glyph representing a character of type size ten is smaller than one framing the same glyph representing the character of type size twelve.
In traditional Japanese typesetting, the layout of a document is created on paper with a grid of one-em square boxes in lines, either horizontally or vertically, with space in between the lines to specify a frame of a particular size. A grid of this type is also often referred to as a CJK grid (Chinese-Japanese-Korean grid). In CJK fonts (that is, fonts representing ideographic systems, such as Chinese, Japanese, and Korean) some fonts' glyphs do not fill an embox completely. For example, some Japanese characters, such as punctuation characters, may be only half an em wide while others are a full em wide, and so on.
Tracking is sometimes applied to the CJK Grid, and is expressed in absolute measurement units (such as mm, points, and so on). When such tracking is applied, the escapement (that is, the distance between the glyph's leading edge and its trailing edge) is changed for one or more glyphs. The result of the tracking is a change of visual appearance, giving the impression that spacing has been inserted or deleted between characters in the line of text. In DTP software applications, tracking is typically applied equally to each glyph; this is often referred to as grid tracking. For non-full width glyphs, this means that too much tracking may be applied. Also, Japanese typesetting conventions dictate that tracking be applied only to non-Roman characters, but conventional grid tracking cannot distinguish between Roman and non-Roman characters, and thus Roman characters often appear to be tracked too much.
Furthermore, in Japanese, so-called mojikumi spacing is generally applied, which refers to the adjustment of the width of characters in the text based on their context in a line of characters. Mojikumi aki refers to spacing that is added between two characters in accordance with their type, or spacing that is added before or after the last character of a line. Mojikumi tsume, on the other hand, refers to spacing that is taken off the left or right sides of a character in order to correct for the difference between a standard for full-width punctuation (e.g., JISx4051-1995) and a font definition for full-width punctuation, and in order to prepare for mojikumi aki to be added. In grid tracking, the tracking is typically applied to the glyphs' trailing edges after mojikumi tsume has been subtracted from and mojikumi aki has been added to the glyph's width. Consequently, the glyphs appear to be lopsided and do not present an aesthetically pleasing view to a user.